Disagree. Tumbleweed moves, and anyone who gives it any notice while driving is putting others at risk. Any sane system ought to be able to recognize tumbleweed and give it the appropriate lack of attention.
I think massive improvements are made to safety when object collision is context aware. Heck, in my driving instruction manual they had an ordering of, "What to hit in an emergency situation," went something like "Animals, ditch, traffic on same flow pattern, structures (buildings, poles), pedestrians, oncoming traffic."
An even more obvious use of contexts: There are two objects, a bag and a baby. You have to hit one, which one do you run over? I think it is possible to build systems that make better decisions than chance in this kind of circumstance.